Converging-diverging nozzles are commonly used to discharge a fluid, typically a gas, to produce a fluid jet which, in turn, creates thrust. For example, such a fluid jet may be used to control the attitude of an airborne vehicle.
Such nozzles typically have a converging entrance section, a narrowed throat section, and a diverging exit section. Each of these sections is typically of fixed dimension and proportion, and the flow of fluid is controlled by an upstream valve having relatively-slidable parts or small-area orifices. In some applications, contaminants in the hot gas, possibly molten aluminum, may foul these sliding parts and/or orifices.
Accordingly, it would be generally desirable to provide an improved thruster nozzle which is relatively insensitive to contaminants in the discharged fluid, which avoids relatively-sliding parts and small orifices, which is generally self-cleaning, and which affords the capability of selectively varying the flow therethrough at the throat.